This invention relates to the field of drive means for oscillating spouts. More particularly, this invention relates to a new and improved apparatus for driving an oscillating spout for a shaft furnace, the spout being capable of pivoting about two orthogonal axes under the action of a pivoting control arm.
Apparatus of this general type has been described in French patent application No. 80 13 890, corresponding to U.S. Pat. No. 4,306,827 which relates to an apparatus for the distribution of charge material in a blast furnace. U.S. Pat. No. 4,306,827 discloses a preferred embodiment wherein the control arm is mounted outside the furnace head. A transmission device which translates the movement of the control arm to the spout is constructed so that the distribution spout and the control arm are always parallel to each other. To distribute the charge material in a circular trajectory, the control arm turns about a vertical axis parallel to the vertical axis of the furnace about which the spout is required to turn. In order to modify the angle of inclination of the spout which, in turn, modifies the radius of the circular trajectory in which the charge material is deposited, a change is made to the angle of inclination of the control arm in relation to its central axis of rotation. An intermediate lever together with the control arm form a rotating hinge with a variable angle of opening (i.e, the included angle). It is this angle of opening which determines the angle of inclination of the control arm and that of the spout in relation to the vertical axis of the furnace.
Unfortunately, despite its simple design, the driving device for the control arm of U.S. Pat. No. 4,306,827 does not allow the distribution spout to be oriented vertically (i.e., it does not enable the charging material to be deposited in the center of the charging surface). Vertical orientation of the spout can only be achieved by positioning the hinge formed by the intermediate lever and the control arm to form an angle of 180.degree. such that the driving rod, the intermediate lever and the control arm are all aligned with one another. Although it is possible to accomplish such an alignment, it is thereafter impossible to move the elements out of this vertical positioning in a controlled manner, since a force exerted on the driving rod, no matter how great, cannot effect controlled modification of the hinge angle once the angle has reach 180 degrees. Only a force directed from the side would be able to unlock the vertical orientation.